Alternating electric switch



May 23, 1944.

D. W. SCOFIELD ALTERNATING ELECTRIC SWITCH 'Filed April 6, 1942 3 Sheets-Sheet 1 )COMICI Mscoffeza AT RNEY lMly 23 1944 D. w. scoFlELD 2,349,522

ALTERNATING ELECTRIC SWITCH Filed April 6, 1942 3 Sheets-Sheet 2 INVENTOR onad )fn/Scofield BY ATTW May 23, 1944- D. w. scoFn-:LD 2,349,522

ALTERNATING ELECTRIC SWITCH Filed April 6, 1942 3 Sheets-Sheet 3 lNvENTo'R .Donad W Scofz'eZJ Patented May 23, 1944 ALTERNATING ELECTRIC SWITCH Donald W. Scofield, Detroit, Mich., assigner to Square D Company, Detroit, Mich., a corporation of Michigan Application April s, 1942, serial No. 437,815

(ci. zoe-) 11 Claims.

.tomatically set into operation to assist the active pump to carry it; or, if one fails, the other will,

for a normal load, operate intermittently and ,for abnormal loads, will run continuously; -the failure of one not affecting the ability of the other to operate, a desirable safety feature.

One object of the present invention is to provide improved control mechanism for effecting alternate or sequential operation of a pair of electric motor driven pumps under normal operating conditions and for eiecting dual operation of the pumps under abnormal operating conditions.

Another object of the present invention is to provide an improved form of control mechanism for automatically controlling the operation of the electric motor driven pumps in a predetermined sequence.

Another object of the present invention is to provide an automatic control mechanism of simple and economical construction for sequentially operating a pair of electric switches.

Other objects and features of the invention will be readily apparent to those skilled in the art from the following specifications and appended illustrating certain preferred embodiments of the invention in which: v

Figure 1 is a front elevational view of the control mechanism according to the present invention.

Figure 2 is a sectional view taken on the line tion and the left hand switch closed.

icv

Figure 'l is a view similar to Figure 6 but with the left hand switch open and right hand switch closed.

Figure s is e view similar te Figure 6 but with both switches in closed position.

Figure 9 is a schematic view illustrating the application of the invention to a pumping system.

The control mechanism as illustrated in the drawings comprises a housing I formed of a generally U-shaped base 2 of sheet metal and a generally U-shaped enclosing cover 3, with the cover 3 being secured to the base 2 by studs 4 passing through the cover and threaded into flanges 5 provided upon opposite legs 6 and 1 of the base 2. Supported upon base 2 in side by side relationship are a pair of identical electrical switching units 8 and 9. Since the switching units 8 and 9 are identical, only the unit 8 will be described in detail. The switching unit 8 comprises a. supporting bracket II rigidly secured to the base 2 by welding. An insulating member I2 having a recess I 3 therein divided by a barrier wall I4 is mounted upon bracket II by a pair of studs I5. Stationary contact elements I6 are provided within the recess I3 on either side of the barrier wall I4. An operating lever I'l pivotally engages leg I8 of the supporting bracket II. Spaced apart members I 9 and 2| are upwardly bent from bracket II with each pressed out as at 22 to provide a notch therein for receiving the ends of the leg portions 23 of a contact lever or member 24 whereby the contact lever 24 will be pivotally supported. A generally U- shaped fibre piece 25 is secured to the lever 24 and carries the contact elements 28 on each leg thereof for cooperation with the stationary contacts I6 for making and breaking electrical circuits therethrough. Pivotally mounted within notches in leg portions 21 of lever 24 is a flipper member 28. A tension spring 29 interconnects the operating lever Il and the iiipper member 28 and serves to maintain the operating lever I1, the contact lever 24 and the flipper member 28 in assembled relationship, for the force exerted thereby biases the operating lever Il into engagement with bracket Il and the contact lever 24 and the flipper member 28 into their respective bearings. Clockwise movement of the operating lever I1 by means to be hereinafter described eiIects movement oi.' the end oi spring 28 secured thereto to carry it across the pivot of flipper member 28, thereby changing the direction of the line of force of the spring to effect a snap movement of the ipper member 28 to carry the end of the spring 29 secured to the iiipper through the pivot of the contact lever 24. The free end of the ipper 28 in its snap movement will strike flange 3| of the contact lever a hammer blow substantially simultaneously with the movement of the end of spring 29 through the pivot of the contact lever 24 to eiect a snap movement of the contact lever in a counter-clockwise direction to its Oi position. To limit the counterclockwise movement of the contact lever 24, the lower edge of leg portion 21 of the contact lever engages a pin 32 provided upon base 2. A generally L-shaped member 33 disposed between the switching units 8 and 9 and secured to the base 2 by a stud 34 carries a cross piece 35 engageable by the operating levers I1 to determine the extent of clockwise movement thereof. To eiect actuation of operating levers I1, pieces 36`and 31 are welded to the under sides of the levers I1 and are bent as at 38 and 39, the bent portions 38 and 39 being substantially normal to the planes of the faces of the operating levers I1. The adjacent vertical edges of the portions 38 and 39 are notched as at 4I and 42. An actuating member 43 comprising a pair of parallel plates 44 maintained in spaced relationship by a pair of pins 45 and 46 disposed near either extremity of the plates 44 is operatively associated with the operating levers I1 of both switching units 8 and 9, the pins 45 and i6 being receivable respectively by the notches 6I and '42 of the members 38 and 39, thus providing a pin and slot connection between the actuating member i3 and the operatingdevers I1, as is illustrated in Figure 4. A spring 411s coiled about each pin 65 and 46, and extends therebetween and is permanently bent as at i8 for a purpose to be hereinafter described. The plates 44 are each centrally provided with a horizontal slot 69, which slots are adapted to slideably receive a pin 5l mounted at the upper end of a reciprocating member 52. The reciprocating member 52 comprises a pair of elongated members 53 and extends from the interior of the housing I through aligned openings in base 2 and the upper face of a mounting bracket 55 upon which the base 2 is supported, to the exterior. The lower extremities of the members 53 are pivotally connected to an actuating lever 55 by a pin 56 whereby an operative connection is effected between the actuating member 63 and the actuating lever 55; the actuating lever 55 in turn is pivotally secured to a supporting element 51 carried by the mounting bracket 54. The lever 55 includes a piece 58 having a portion thereof return bent upon itself to provide an opening as at 59, through which opening 59 a float rod 6I extends. -A pair of hex nuts 62 are mounted upon the float rod at either side of the piece 58, being spaced apart to provide a lost motion connection ananas other liquid reservoir and is movable in response in its lower position, a rise in the liquid levelin the container, the contents of which are to be controlled, will effect an upward movement ofthe `iioat 63 and the oat rod 6I to rotate lever 55 counter-clockwise exerting a force which pulls connecting member 52 generally downward. As shown in Figure 1 pin 5I which connects the member 52 and the actuating member 43 lies within slot 49 and to,the left of the center line thereof whereby the force exerted on pin 5I by the member 52 in its downward movement acts to eiect rotation of the actuating member 43 and the pin 45 carried thereby in a counterclockwise direction about pin 46. The pin 45 being received within notch 4I of piece 38 will effect a counter-clockwise movement of this piece to thereby move operating lever I1 of the switch ing unit 6 to which it is connected also counterclockwise from the position it occupies as shown in Figure 2 to carry the line of force of spring 29 through the pivots of flipper 28 and contact lever 23 to eiect snap movement of the movable contact 26 into engagement with stationary contact I6 to start the motor 64 that is in circuit therevwith to eect the operation of its associated pump 66 to begin reduction of the level of the -liquid in the container. The various elements will then occupy the position illustrated in Figure 6 at the time operation of the pump 66 is effected. With a fall in the level of the liquid, lever 55 will be rotated clockwise by the oat rod 6I and the pin 5I will first be moved from the position of Figure 6 in which it occupies the left hand end of the slot, diagonally upwardly past the centerline and to the right hand end, so that continued reduction of the liquid level will result in the force transmitted from the float and through the members 52 and 55 being exertedupon the upper dening edge of slots 49. to rotate the member 33 clockwise about pin 46 to carry pin 45 in a like direction. When the liquid level has been restored to normal, pin 45 in engagement with operating lever I1 of switching unit 8 will have eiected clockwise movement of the lever to a point where it will perform the switching operation to open the contacts and stop the motor 64 and pump 66.

With another rise in' the liquid level the lever y 55 will again be rotated eiecting downward movement of the member 52 and of pin 5I carried thereon. Since the pin 5I lies to the right of the center of the member 43, the applied force will rotate the member 43 clockwise about pin 45 effecting clockwise movement of pin 46. Pin 46 being in engagement with the member 39 will move it to eiect movement on the operating lever I1 of the switching unit 9 to snap the movable contact thereof as described into the circuit making position illustrated in Figure 7, thus starting the second motor 65 to drive pump 61 to begin the work of reducing the liquid level.

With the falling of the liquid level the iioat 63 will cause the lever 55 to rotate clockwise, moving member 52 upwardly to first carry pin 5I from the right hand end of slot 49 diagonally upwardly past the center line of the slot and to the left hand end so that the force provided by the oat 63 will be transmitted through members 52 and 55 to act upon the actuating member 43 tion illustrated in Figure 1.

vibration or through the shock of a blow, to there- ,fby disrupt the sequence of operation. The pin 5I can be moved from one side to the other only through the force provided by the oat 63 which is suiilcient to overcome the tension in spring 4l. Thus, when once actuated to one side or the other of the slot 49, the pin 5I will remain there and the force of float 63 transmitted through members 52 and 55 will be eifectively applied at the proper side of the centerline to eect the rotation d the actuating member 43 in the desired direction about the propex pivot to thereby operate the switching units l and 9 in proper sequence. Assume the actuating member 43 to have been rotated clockwise about pin 45 so that the control mechanism ail'ects the position illustrated ln Figure 7, and assume conditions to be abnormal so that pump 61 controlled by switching unit 8 is not capable of properly caring for the load, whereby the liquid level continues to rise. Under these circumstances, lever 55 will be rotated further than normally necessary in a counterclockwise direction to exert a continued force upon the actuating member 43 throgh pin 5l to rotate the actuating member about pin 46, moving pin 45 and thereby operating lever Il of switching unit 8 to thus eifect a closing of the contacts thereof to put the second electric motor driven pump 66 into operation. With both pumps 66 and 61 running, the control mechanism assumes the position of Figure 8.v It is to be noted that under abnormal conditions, the lever 55 rotating in but one direction eifects alternate rotation of the actuating member 43 rst about pin 45 and then about pin 46. Both of the pumps 66 and 6l will continue to run until the load falls to a point where but one pump is necessary to handle the work. When the load falls to this point, lever 55 rotates clockwise to exert force through member 52 and pin 5| upon l the actuating member 43 to rotate this member about pin 45 and thus actuate the operating lever Il of the switching unit 9 to effect disengagement of the contacts thereof to stop pump 6l, but leaving pump 66 active to assume the burden.

If either of the switching units 8 or 9 or the electric motors or pumps should fail due to any reason, the actuating lever 55 and the connecting means 52 will still be eiective to rotate the actuating member 43 to bring about a movement of the operating lever 'Il of the switching unit still effective to operate the electric motor driven pump controlled thereby, intermittently for normal loads and, if an abnormal load should arise, to hold the operable switching unit closed to run the pump continuously. Thus, loads placed upon the pumping system will be cared for unless both pumping units should break down.

A control mechanism has thus been provided which will operate a pair of electric motor driven pumps in alternate sequence to divide the work of caring for normal loads on the system and which will effect operation of both of the pumps in unison upon the occurrence of abnormal conditions when one of the pumps cannot handle the work imposed upon it.

While certain preferred embodiments ofithe control mechanism have been speciilcally disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. Control means for operating a pair of electric motors, and including a pair of electric switches. each of said electric switches controlling the operation of one of said motors and each comprising relatively movable contacts and an operating lever for effective relative movement of said contacts, mechanism for operating said electric switches alternately and in sequence, opening one before the other is closed, said mechanism comprising a rotatable actuating member supported by said pair of operating levers, and means for rotating said actuating member in opposite directions to effect the alternate operation of said pair of operating levers.

2. Control means for operating a pair of electric motor driven pumps, and including a pair of electric switches, said electric switches comprising stationary and movable contacts and an operating lever movable to move said movable contacts into and out of engagement with said stationary contacts, means for effecting alternate operation of said electric switches wherein one is opened before the other is closed, said means comprising a rotatable actuating member having a pivotal connection with the operating levers of both of said electric switches, and reciprocating means operable on alternate strokes to pivot said actuating member alternately about its connections with said pair of operating levers to eilect alternate movement of said operating levers.

3. Control means for operating a pair ofelectric motors and including a pair of electric switches said electric switches comprising relatively movable contacts and an operating lever for effecting movement of said contacts to separated and to engaged position, means for operating said operating levers alternately whereby but one electric switch will be in operation at a ltime, said means comprising a rotatable actuating member for moving said operating levers and adapted to rotate about a pair of spaced pivots and a reciprocating member adapted to apply force at each side of the center of the actuating member for rotating said actuating member in opposite directions about said spaced pivots to effect alternate operation of said pair of switches.

4. Control means for a pair of electric motors, and including a pair of electric switches, each of said electric switches controlling the operation of one of said motors and each comprising relatively movable contacts and an operating leverl for effecting relative movement o) said contacts, mechanism for operating said electric switches alternately and in sequence, opening one before the other closes, said mechanism comprising an actuating member for moving said operating levers, a pair of spaced pivots about each of which said actuating member is adapted to rotate, and means having a slidable connection with said actuating member and movable to predetermined positions upon said actuating member to eifect rotation thereof in opposite directions about said spaced pivots to alternately move said pair of operating levers.

5. In control mechanism for operating a pair of electric motor driven pumps, apair of electric switches for controlling the operation thereof and comprising stationary and movable contacts and an operating lever movable to move said movable contacts into and out of engagement with said member operable within said slot, and reciprocating means for moving said movable member on alternate strokes to predetermined positions within said slot to apply force to pivot said actuating member alternately about said spaced pivots to eifect alternate movement thereof of said operating levers.

6. Control means for a pair of electric motor driven pumps, and including a pair of electric switches for controlling the operation of said pumps and each of said switches comprising stationary and movable contacts and an operating .lever for effecting Vengagement and disengagement of said contacts, means for effecting alternate operation of said electric switches, opening one before closing the other, said means comprising a rotatable actuating member having a pivotal connection with the operating levers of both of said electric switches, said actuating member being provided with a slot therein, a movable member operable within said slot, and reciprocating means for moving said member on alternate strokes to predetermined positions within said slot to apply force to pivot said actuating member alternately about said connections with said pair of operating levers to effect alternate operation of said operating levers, and spring means to maintain said movable member in the predetermined position to which it was actuated until a switching operation has been effected by one of said operating levers.

7. Control means for operating a pair of electric motor driven pumps, and including a pair of electric switches and each of said switches comprising cooperating contacts for making and breaking an electrical circuit and an operating lever for effecting cooperation of said contacts, mechanism for operating said electric switches alternately and in sequence, opening one before the other closes, and comprising a rotatable actuating member supported by said operating levers, and a movable member having a. slidable connection with said actuating member and movable to predetermined positions upon said actuating member to effect rotation thereof in opposite directions to alternately move said operating -levers to engaged position, and spring means carried by said actuating member and effective to maintain said movable member in the predetermined position into which it was moved until one of said operating levers has beenmoved to engaged position.

8. Control means for operating a pair of electric motor driven pumps, and including a pair of electric switches, and each of said switches comprising cooperating contacts for making and breaking an electrical circuit and an operating lever for effecting cooperation of said contacts, means normally effective to open and close said electric switches in alternate sequence whereby but one switch will be in operation at a time, said means comprising an actuating member having a pivotal connection with the operating lever of each of said electric switches, a movable member operatively connected to said actuating member to pivot said actuating member alternately about said connections with said operating levers, said actuating member when pivoted about a connection with one operating lever being effective to operate the other operating lever to engaged position. and means operable on said movable member after one operating lever has been moved to engaged position to pivot said actuating member about its connection with said moved operating lever to move the second switching means also into engaged position to care for an abnormal pumping condition.

9. Control means for a pair of electric motor driven pumps, and including a pair of electric switches for controlling the operation of said pumps and each of said switches comprising stationary and movable contacts andan operating lever movable to move said movable contacts into and out of engagement with said stationary contacts, sequence controlling mechanism cooperating with said switches for controlling the' sequence of operation of the motors, said mechanism comprising a rotatable actuating member having a pivotal connection with the operating levers ofboth of said electric switches, and reciprocating means operable on alternate strokes to pivot said actuating member alternately about said connections with said pair of operating levers to effect alternate movement thereof to engaged position, and means operative on the arising of an abnormal pumping condition to move said reciprocating means after it has pivoted said actuating member about one of said connections 'to move an operating lever to engaged position to then pivot said actuating member about the connection with said operated operating lever to movev the other operating lever also into engaged position.

10. In control means for eecting alternate and sequential operation of a pair of electric switches, said electric switches comprising stationary and movable contacts and an operating lever for eifecting engagement and disengagement of said contacts, an actuating member operatively secured to each of said operating levers, a movable member slidably connected to said actuating member and engaging said actuating member at a first point, means adapted on the occurrence of a predetermined conditions to apply force upon said movable member to move said actuating member to operate one of said operating levers to engaged position, said means upon the removal of said operating condition acting to first move said movable member to a second point on said actuating member and then to apply force thereon to operate said actuating member to move the engaged operating lever to disengaged position, said movable member being moved to engage the actuating member at said second point to make said movable member effective, upon a. reoccurrence of said predetermined condition, to move said actuating member to move the other of said operating levers to engaged position.

11. In control means for effecting alternate and sequential operation of a pairA of electric switches, said electric switches comprising relatively movable contacts and an operating lever for effecting separation and engagement of said contacts, an actuatirig member operatively secured to each of said operating levers. said actuating member being slotted, a movable member occupying a first position in said slot, reciprocating means adapted on the occurrence of a predetermined condition to move in a. first direction to apply force upon said movable member to move said actuating member to operate one of said operating levers to engaged position, said reciprocating means in its return movement upon 5 the removal of said predetermined condition acting to first move said movable member to a, second position in said slot and then to apply force thereon to operate said actuating member to move the engaged operating lever to disengaged position, said movable member in said second position being adapted upon a reoccurrence of said predetermined condition to be moved by said reciprocating means moving in said first direction to move the other of said operating levers to engaged position. l'

DONALD W. SCOFIELD. 

